Depth is a property referring to how deep a feature is according to charted depth, measured in metres. For shallow depths, such as some fords, a decimal value will be needed - e.g. 0.05 for 5 cm. In most cases, the depth of a feature in the ocean is referred to LAT (Lowest Astronomical Tide). For rivers, canals, and inland lakes this might be different. Rivers and canals with water level gauges will have a defined zero value where depths should be referred.